Optics Help To Clear Arteries

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Optics Help To Clear Arteries

A new treatment that activates a drug with a high intensity light has been shown to dissolve the fatty deposits that clog leg arteries.

The drug, called lutetium texaphyrin, was developed by Pharmacyclics in Sunnyvale, California. It is used in conjunction with a high intensity red light to clear the artery.

The treatment uses an optical fiber tube to deliver light directly to obstructed vessels. Doctors insert a tiny fiber-optic filament – a little thinner than a paper clip – through a small slit in the artery and maneuver it to the blockage, which delivers the light to the interior of the vessels.

In Phase I studies, Stanford University scientists applied the treatment, which was originally tested as a cancer therapy, to 16 patients. Twelve showed significant circulation improvement.

Four weeks later, doctors looked at the patients' arteries using intravascular ultrasound. They saw an increase in circulation of better than 10 percent, while plaque deposits decreased anywhere between 10 and 74 percent in 12 of the 16 patients.

Plaque is the enemy here, since it is the material that clogs arteries. And hope rests in this new treatment because only specific cells – including cancer cells and certain cells in plaque – absorb the drug.

"What's really exciting is that it targets the cells that are the cause of atherosclerosis," said Daniel Adlman, senior director for clinical research at Pharmacyclics. "The white blood cells in the arterial walls take up the Antrin (the drug's trademark name), and the drug causes those cells to disappear and die."

The procedure treats the underlying cause of atherosclerosis, which is inflammation. "No other therapy does that," Adlman said.

Scientists are hailing the treatment as an alternative to angioplasty because it doesn't cause injury to the vessel, which can cause it to re-clog. Angioplasty is currently the most common treatment for severe arterial blockage, and involves inflating a balloon inside the clogged vessel, crushing the plaque and opening a channel for blood flow.

"This treatment stays away from harmful side effects such as restenosis, which happens after angioplasty – a process by which the angioplasty blood vessel clogs up," said Mahmood Razavi, an assistant professor of radiology at Stanford. Razavi presented the research Tuesday at the Society of Cardiovascular and Interventional Radiology's annual scientific meeting in Orlando, Florida. "The beauty of this procedure is it avoids what causes re-clogging."

"The benefit is that unlike everything else we currently do, this one in theory doesn't injure the blood vessels," said Stanley Rockson, an assistant professor of medicine at Stanford. "That's really what's plagued everything we've done until now. [Other treatments] will make the blood vessel larger, but it re-narrows because it's injured from the treatment."

Up to 20 percent of patients over 70 have circulation problems in their legs, said Rockson. These types of problems make it difficult or impossible for patients to walk without pain.

The researchers plan to show the procedure's efficiency against a much bigger enemy – coronary artery blockage – as part of the Phase II studies planned for the fall.

Pharmacyclics is also seeking FDA approval on a different version of the same drug for treating breast cancer that has spread to the skin.